Casting of ingots

ABSTRACT

Splash during teeming ingots is minimized by locating a foam pad in the ingot mould prior to use.

United States Patent [72] Inventors Roger Mervyn Hilton;

John Frances Xavier Watkinson, both of Birmingham, England [21] Appl. No. 876,616

[54] CASTING 0F INGOTS 11 Claims, No Drawings [52] U.S.C1 164/133,

[51] Int. Cl B22d 37/00 [50] Field of Search 164/47, 133, 271; 249/206 [56] References Cited UNlTED STATES PATENTS 3,182,363 5/1965 Ferree 164/133 3,195,853 7/1965 Ferree 249/206 Primary Examiner-J. Spencer Overholser Assislan! Examiner-John E. Roethel AnomeyWo1fe, Hubbard, Leydig, Voit & Osann, Ltd.

ABSTRACT: Splash during teeming ingots is minimized by locating a foam pad in the ingot mould prior to use.

CASTING F INGOTS The present invention relates to the casting of ingots, particularly to the casting of steel ingots.

It is important in the casting of molten metal to form ingots to produce an ingot surface as free from inclusions and imperfections as possible, since surface defects can lead to difficulties in rolling the ingots to produce billets and a high rejection rate of the metal sheet, strip or the like finally produced.

It is well known that bottom poured ingots generally have a markedly improved surface quality as compared with top poured ingots, but for many reasons it is neither practical nor convenient to adopt to a bottom pouring technique in order merely to achieve improved surface quality. It is believed that the poor surface quality of top poured ingots results from the extreme turbulence and splashing during teeming especially near the commencement of teeming.

Many methods have previously been proposed to decrease this turbulence and splashing, but none has been found which is wholly satisfactory. Particular effort has been directed to reducing splash, such as the provision of splash cans, metal tubes, wood shavings, silicate-bonded corrugated cardboard and sawdust in the base of the mould.

According to the present invention there is provided a method of reducing splash at the commencement of molten metal teeming into an ingot mould which comprises, prior to commencement of teeming, locating in the ingot mould a pad of foam material. Preferably the foam material is of organic nature, or contains organic materials. In this case, decomposition of the foam by the heat of the molten metal created a reducing atmosphere in the ingot mould, which it is believed, helps also to improve the surface quality of the final cast ingot. Suitable foam materials are foamed polyurethanes and polystyrenes, in which flame retardent additives are desirably included. Alternatively the foam pad may be a pad of foamed slag material.

The thickness of the foam pad will vary depending upon its thermal resistance and the height of the ingot mould in which it is used (i.e. the height from which the metal stream falls). However, it will generally be of the order of at least cm. in thickness and it may be desirable to substantially fill the ingot mould with the foam. It is usually desirable to use a fairly spongy foam to absorb the impact of the molten metal efi'rciently.

The foam pad may be prepared externally of the mould and introduced into the mould, or may be created in situ in the mould by including in the mould the precursors for the foamed material and carrying out the foaming operation in the mould itself by methods known per se for the production of foamed products.

The foam pad of the present invention, in addition to its use in preventing splash, may also be used as a carrier for various metal treatment agents. For example there may be distributed in the pad, fluxing agents (e.g. fluorides, fly ash) and iron rimming, killing and deoxidizing agents (e.g. iron mill scale, hematite, various other oxygen containing compounds and powdered aluminum).

It is found that ingots cast using the method of the present invention have greatly improved surface quality, with a very low incidence of scabs, cracks and inclusions.

We claim:

1. A method of reducing splash at the commencement of molten metal teeming into an ingot mould which comprises, prior to the commencement of teeming, locating in the ingot mould a pad of foam material selected from the class consisting of foamed polyurethane and foamed polystyrene.

2. A method according to claim wherein the foam material includes flame-retardent additives.

3. A method of reducing splash at the commencement of molten metal teeming into an ingot mould which comprises, prior to the commencement of teeming, locating in the ingot mould a pad of foam material comprising foamed slag.

4. A method according to claim 1 wherein the pad of foam material is at least l5-cm. thick.

5. A method according to claim I which includes the step of introducing foam precursors into the ingot mould and generating said pad of foam material in situ.

6. A method according to claim 1 in which the pad of foam material includes metal treatment agents.

7. A method according to claim 6 wherein the said agents are selected from the class consisting of fluxing agents, and iron rimming, killing and deoxidizing agents.

8. A method according to claim 3 wherein the pad of foamed slag is at least 15 cm. thick.

9. A method according to claim 3 which includes the step of introducing foam precursors into the ingot mould and generating the pad of foamed slag in situ.

10. A method according to claim 3 wherein the foamed slag includes metal treatment agents.

11. A method according to claim 10 wherein said metal treatment agents are selected from the class consisting of fluxing agents, and iron rimming, killing and deoxidizing agents.

* I! I t t 

1. A method of reducing splash at the commencement Of molten metal teeming into an ingot mould which comprises, prior to the commencement of teeming, locating in the ingot mould a pad of foam material selected from the class consisting of foamed polyurethane and foamed polystyrene.
 2. A method according to claim wherein the foam material includes flame-retardent additives.
 3. A method of reducing splash at the commencement of molten metal teeming into an ingot mould which comprises, prior to the commencement of teeming, locating in the ingot mould a pad of foam material comprising foamed slag.
 4. A method according to claim 1 wherein the pad of foam material is at least 15-cm. thick.
 5. A method according to claim 1 which includes the step of introducing foam precursors into the ingot mould and generating said pad of foam material in situ.
 6. A method according to claim 1 in which the pad of foam material includes metal treatment agents.
 7. A method according to claim 6 wherein the said agents are selected from the class consisting of fluxing agents, and iron rimming, killing and deoxidizing agents.
 8. A method according to claim 3 wherein the pad of foamed slag is at least 15 cm. thick.
 9. A method according to claim 3 which includes the step of introducing foam precursors into the ingot mould and generating the pad of foamed slag in situ.
 10. A method according to claim 3 wherein the foamed slag includes metal treatment agents.
 11. A method according to claim 10 wherein said metal treatment agents are selected from the class consisting of fluxing agents, and iron rimming, killing and deoxidizing agents. 